To the side of the chair I positioned by Nikon SB-800 with Yongnuo YN-622-RX on a light stand, facing away and pointing into a gold lighting umbrella that was open only just enough to allow the flash to fit inside the opening.

The opening of the brolly pointing to the side of the chair and ultimately my face.

The SB-800 was set to a suitably low output.

Before shooting the image I disabled the flash and setup my focus on the chair and then switched to manual focus on the lens so it wouldn't try to autofocus when I took my shot.

Aperture was set at f1.8 as I wanted a nice, shallow depth of field.

I gradually increased the shutter speed as I fired off some test images until it resulted in a completely black image.

I then enabled the flash, set the camera to 5 second timer, took my seat, pressed the shutter and positioned myself ready for the timer to fire the shutter and flash.

Editing

I performed a minor edit to the image in Adobe Photoshop CC 2015.

I duplicated the photograph into a new layer, set the layer mode to "overlay" and reduced the opacity until I was happy with the increased visible detail.

I then used the eraser tool on the new layer to erase around my eye in order to lighten that section and allow it to stand out a little.

Notes

I wanted to shoot this image with one of our silver umbrellas but at the time I could only find a gold one.

After looking at the results; I do rather like the warmth that it gives to the final image and I'm glad I couldn't place the umbrella I'd started out to use.

If you're not overly happy with the added warmth of a gold umbrella you can always edit a B&W version as below.

The other time that I tried "The Invisible Black Background" technique; I shot a few pictures of our little Blackmagic Design Pocket Cinema Camera rig whilst using a silver umbrella.

As you can see; the silver umbrella gives a nice, clean, neutral light and shows off the details of the camera setup and the vivid red coloured elements really well and is much better in this situation.

When I shoot some more of these images I will take some "behind the scenes" images to show the setup better than I can describe it.